A CNT formed from only carbon atoms is a material having excellent electrical properties, thermal conductivity and mechanical properties. A CNT is very light and extremely string and has excellent flexibility and restoring force. A CNT having these types of excellent properties is a very attractive and important material for industrial use.
A CNT is dispersed uniformly in a solution in the case where a CNT is used as an industrial material. For example, it is possible to manufacture nano-composite in which CNTs are dispersed uniformly in a polymer matrix by dissolving a polymer in a solution dispersed uniformly with the CNTs. In addition, when manufacturing electronic devices such as transistors, electron emission sources or secondary batteries, for example, a method exists whereby a suspension solution in which CNTs are dispersed in a solution is created, and after forming a suspension solution pattern on a support composite which is used as a substrate using a printing technology such as cast, screen or inkjet printing, the solution is dried, removed and a desired shape is obtained.
However, a method has still not been established for sufficiently dispersing nanotubes in a solution. This is because CNTs bundle together or clump into roping due to the Van der Waals force between mutual CNTs. Therefore, despite the unique and useful properties of CNTs, it is extremely difficult to manufacture a polymer type nano-composite dispersed uniformly with CNTs which makes actual application to various uses of CNTs difficult.
In order to disperse CNTs uniformly a method is disclosed in Japanese Laid Open Patent 2009-149832 of a processing a mixed product including 10 mg of a double-walled CNT agglomerate, 30 mg of sodium polystyrene sulfonate and 10 mL of water using an ultrasonic homogenizer and after centrifugal processing at 20000 G and when 9 mL of a supernatant is sampled, the CNT agglomerate in which the contained amount of the CNT agglomerate within the supernatant becomes 0.6 mg/mL or more is used as a material for a transparent conductive film. In this way, an ultrasonic process was performed conventionally well enough for dispersing CNTs yet there was a problem whereby the CNTs easily broke when exposed to ultrasonic waves.
In addition, a stable CNT dispersion is disclosed in Japanese Laid Open Patent 2007-169120 in which a single-walled CNT is not formed at all as a bundle or exists as a bundle comprised from a small amount of single-walled CNTs by using an aprotic organic dispersion medium and a wholly aromatic polyamide are used as an aggregation inhibitor. In these conventional technologies, a uniform CNT dispersion was obtained by either inhibiting or unwinding an aggregation of CNTs when manufacturing a CNT dispersion.